Electronic irrigation controllers have long been used on residential and commercial sites to water turf and landscaping. They typically comprise a plastic housing that encloses circuitry including a processor that executes a watering program. Watering schedules are typically manually entered or selected by a user with pushbutton and/or rotary controls while observing an LCD display. The processor turns a plurality of solenoid actuated valves ON and OFF with solid state switches in accordance with the watering schedules that are carried out by the watering program. The valves deliver water to sprinklers connected by subterranean pipes.
There is presently a large demand for conventional irrigation controllers that are easy for users to set up in terms of entering and modifying the watering schedules. One example is the ICC™ irrigation controller commercially available from Hunter Industries, Inc., the assignee of the subject application. Commercial controllers may allow the user to enter multiple watering programs. Each watering program consists of one or more watering schedules. The user simply enters the start times for a selected watering program, assigns one or more stations to the watering program, and schedules each station to run a predetermined number of minutes to meet the irrigation needs of the site. The problem with conventional irrigation controllers is that they are often set up to provide the maximum amount of irrigation required for the hottest and driest season, and then either left that way for the whole year, or in some cases the watering schedules are modified once or twice per year by the user. The result is that large amounts of water are wasted. Water is a precious natural resource and there is an increasing need to conserve the same.
A conventional irrigation controller of the type that is used in the commercial market includes a seasonal adjustment feature. In some controllers, there is one seasonal adjustment that is an overall adjustment for all stations in the controller that is changed by the user and adjusts the overall watering as a percentage of the originally scheduled cycle times. This feature is typically a simple global adjustment implemented by the user that adjusts the overall watering as a percentage of the originally scheduled cycle times. It is common for the seasonal adjustment to vary between a range of about ten percent to about one hundred and fifty percent or more of the scheduled watering. This is the simplest and most common overall watering adjustment that users of irrigation controllers can effectuate to modify their irrigation requirements through the different seasons. Some commercially available irrigation controllers expand this capability by allowing independent seasonal adjustment of each program. This may be referred to as multiple seasonal adjusts, percentage adjusts by program or water budget by program. Because of this, there is the potential to have several seasonal adjustments that need to be made by the user. With this advanced programming where the user has a separate seasonal adjust for each program, the user may assign stations with similar irrigation requirements to an independent seasonal adjust. For example, all of the stations that irrigate turf in the sun may be assigned to one seasonal adjust. Likewise, all stations that water turf in the shade may be assigned to another seasonal adjustment. This may continue as they add other zones such as those used for potted plants, those used for planters with over head watering, those used for planters with drip, those used for watering trees, etc. While this allows for greater flexibility to perform better irrigation throughout the seasons, it adds to the complexity for the user. Users can move the amount of adjustments down to zero to thirty percent in the winter, depending on their local requirements. They may run the system at fifty percent during the spring or fall seasons, and then at one hundred percent for the summer. The ability to seasonally adjust up to three hundred percent of the scheduled watering accommodates the occasional heat wave when turf and landscaping require significantly increased watering. The seasonal adjustment feature does not produce the optimum watering schedules because it does not take into consideration the amount of moisture that is actually available in the soil for the plants to utilize for healthy growth. Instead, the seasonal adjustment feature is manually set to simply adjust the watering schedules either globally, or by individual programs, to run a longer or shorter period of time based on the existing watering schedules. When the seasonal adjustment feature is accurately re-set on a regular basis, a substantial amount of water is conserved while still providing adequate irrigation in a variety of weather conditions. The problem is that most users do not re-set this on a regular basis, or do not set this correctly, so either a considerable amount of water is wasted, or turf and landscaping die.
In the past, irrigation controllers used with turf and landscaping have used soil moisture data to activate or deactivate irrigation zones based on actual soil moisture conditions. When soil moisture sensors are used with conventional irrigation controllers the sensors typically interrupt the programmed irrigation cycle by breaking the electrical connection between the controller and the irrigation valves when the soil is moist. Some specialized controllers that are designed to work specifically with soil moisture sensors can turn the irrigation on when the soil reaches a dry state, then turns the irrigation off when it reaches a moist state.
While conventional soil moisture based controllers help to conserve water and maintain plant health over a wider range of weather conditions they are specifically adapted to soil moisture sensor control and may not meet other needs of the landscaped area well. Soil moisture sensors that are hooked up to traditional irrigation controllers may simply disrupt the scheduled irrigation by disconnecting the common line to the valves when the soil is moist. In these cases, the irrigation controller turns ON the outputs to the valves when they are normally scheduled to run. If the soil moisture sensor is sensing moist soil conditions, it simply disconnects the electrical circuit to the valve. The controller thinks it is irrigating, but the irrigation process is not happening. This can create confusion for the user when they go to the controller and see that station (X) is on yet they go out to the property to see that the same station is not running irrigation. This can result in calls to professionals to debug the irrigation system when the soil moisture was just keeping the station from running as designed. In these applications, there is no indication on the controller that the soil moisture has disrupted the irrigation process.
In both of the aforementioned circumstances, the systems may require one sensor to be placed in the ground for every zone on the controller. Cables are then run back to the controller through the landscape. Some commercially available irrigation controllers irrigate over forty zones. This requires a substantial cost in materials and labor. Additionally, some conventional irrigation controllers calculate the amount of water used based on the irrigation cycles as they run. When the sensors disrupt irrigation, while the controller thinks it is irrigating, the controller creates erroneous reports of over use of water, when in fact conservation is occurring. In some irrigation controllers, the controller knows the theoretical amount of water scheduled to be applied. As the stations are running, the controller measures this theoretical flow against the actual flow with a flow meter installed on the irrigation site. When the theoretical and actual flow are not within certain parameters, an alarm will indicate that there is a problem with the irrigation system. Soil moisture installations mentioned above will not work with these types of controllers.
In another application one soil moisture sensor is hooked up to a rain sensor input on a conventional type of irrigation controller. In this case, as soon as the soil moisture sensor detects moisture, it shuts the entire controller off. This requires abnormal programming in the controller and also requires the soil moisture sensor to be placed in the last station to be run so the irrigation does not shut off before all stations have irrigated. With this arrangement, watering conservation may not be optimized as all of the previous stations may have run too much water for proper irrigation to have occurred prior to the last station sensing that the soil is moist after just a few minutes of irrigation.